Ventricular tachycardia – an attack of palpitations of the ventricles to 180 beats or more. The correctness of the rhythm is usually saved. During ventricular tachycardia as well as with supraventricular (supraventricular) attack usually begins acutely. Relief of the paroxysm often occurs independently.
The content of the article
Paroxysmal ventricular tachycardia is the most dangerous type of arrhythmia. This is because, firstly, this type of arrhythmia is accompanied by violation of the pumping function of the heart, leading to heart failure. And, secondly, high probability of transition to the atrial or ventricular fibrillation. When such complications terminated the coordinated work of the myocardium, and thus, there is a complete stop of blood circulation. If in this case not to provide resuscitation, followed by asystole (cardiac arrest) and death.
Classification of ventricular tachycardia
According to the clinical classification distinguish 2 types of tachycardias:
- Paroxysmal sustained:
- duration 30 seconds;
- pronounced hemodynamic disorders;
- high risk of developing heart failure.
- Unstable paroxysmal ventricular tachycardia:
- short duration (less than 30 seconds);
- hemodynamic disorders do not exist;
- the risk of developing atrial brillation or heart failure are still great.
Special attention should be paid to the so-called special forms of ventricular tachycardias. They have one common feature. If you encounter such sharply increased the willingness of the heart muscle to the development of ventricular fibrillation. They include:
- Recurrent ventricular tachycardia:
- the renewal of the paroxysms after periods of normal heartbeats with the source of rhythm of the sinus node.
- Polymorphic tachycardia:
- this form may occur in the simultaneous presence of multiple lesions source of rhythm.
- Bidirectional ventricular tachycardia:
- is characterized by either different ways of conducting nerve impulse from a single ectopic focus, or proper interleaving of the two sources of nerve impulses.
- Tachycardia type “Pirouette”:
- the rhythm wrong;
- in type is bidirectional;
- very high HR (heart rate) up to 300 beats per minute;
- the ECG is a wave — like increase with a subsequent decrease in the amplitude of the ventricular QRS-complexes;
- the tendency to relapse;
- at the onset of the paroxysm is defined by prolongation of the interval Q-T (ECG) and the occurrence of early extrasystoles (premature contractions of the myocardium).
The etiology and prevalence of diseases
According to international estimates, approximately 85% of cases, ventricular tachycardia accounts for persons suffering from coronary heart disease (CHD). Two patients out of a hundred suffering from this disease to find the cause is generally not possible. In this case we speak about the idiopathic form. Men are 2 times more exposed to such paroxysms.
There are 4 main groups of causes of paroxysmal ventricular tachycardia:
- Violation of circulation of blood through the coronary arteries:
- myocardial infarction;
- post-infarction aneurysm;
- reperfusion arrhythmias (arise during the reverse recovery of impaired blood flow of the coronary artery).
- Genetic disorders in the body:
- dysplasia of the left ventricle;
- lengthening or shortening of Q-T interval;
- catecholaminereleasing trigger polymorphic ventricular tachycardia.
- Diseases and conditions not associated with coronary blood circulation:
- myocarditis, infarction, and cardiomyopathy;
- congenital and rheumatic heart diseases, the effects of surgical interventions;
- amyloidosis and sarcoidosis;
- overdose of drugs (e.g. cardiac glycosides);
- “athlete’s heart” (changed the structure of the myocardium that develops due to high stress on the heart muscle).
- Other unidentified factors:
- the occurrence of ventricular tachycardia in the absence of all the above conditions.
The mechanism of development of ventricular tachycardia
Science knows three mechanisms for the development of the ventricular paroxysms:
- The mechanism of re-entry. It is the most common cause of arrhythmias. It is based on the re-entry wave excitation area of the myocardium.
- Pathological focus of increased activity (automaticity). In a certain part of the cardiac muscle under the influence of various internal and external factors shaped the ectopic source of rhythm, causing tachycardia. In this case we are talking about the location of an epileptic focus in the ventricular myocardium.
- A trigger mechanism. When it occurs earlier, the excitation of myocardial cells, which contributes to the emergence of a new impetus “ahead of schedule”.
Clinical manifestations of the disease Symptoms of ventricular tachycardia are varied. They directly depend on the duration of the attack and of the functional state of the myocardium. Short paroxysms of perhaps asymptomatic. With longer bouts appear:
- the feeling of palpitations;
- the feeling of “lump in throat”;
- sudden dizziness and unexplained weakness;
- the feeling of fear;
- blanching of the skin;
- pain and burning sensation behind the breastbone;
- frequently observed loss of consciousness (based on insufficiency of cerebral circulation);
- for violation of the coordinated reduction of myocardial occurs of acute cardiovascular failure (ranging from shortness of breath or pulmonary edema and ending with fatal outcome).
In order to determine the type of paroxysmal tachycardia and to ensure that is the place to be this V-shape, quite a few diagnostic methods. The main one is the electrocardiography (ECG).
ECG in ventricular tachycardia There is some indirect symptoms that can suggest the presence of a ventricular type of paroxysmal tachycardia. These include all of the above symptoms, plus some simple physical studies and their results:
- when listening to the heart (auscultation) is a rapid heartbeat with deaf heart tones that are impossible to calculate;
- weak pulse at the radial artery (defined on the wrist) or the lack of it (if not possible “to probe”);
- a sharp decrease in blood pressure (BP). Often, HELL I can’t determine, first, because of its very low level and, secondly, because of too high heart rate.
In the absence of ECG signs of ventricular tachycardia, but these symptoms, it is reasonable to conduct Holter monitoring. One of the main objectives of these two research tools – determining the presence of ventricular tachycardia and its differential diagnosis from forms of supraventricular with aberrant conduction (with enlarged QRS complex).
Differential diagnosis of ventricular tachycardia
Of paramount importance in determining the ventricular tachycardia is its differentiation from supraventricular form with aberrant impulse conduction (as in both types of the QRS complex extended). This need is due to differences in relief of an attack and possible complications. This is due to the fact that paroxysm of ventricular tachycardia is much more dangerous.
Signs of ventricular tachycardia:
- The duration of the QRS complexes of more than 0.12 seconds (ECG in comparison with supraventricular tachycardia complex is wider).
- AV-dissociation (asynchronous atrial and ventricular ECG or by an electrophysiological intracardiac study).
- QRS-complexes are monophasic (rs or qr).
Signs of supraventricular tachycardia with aberrant conduction:
- Three phase (rSR) the QRS complex in the first thoracic (V1) leads.
- QRS duration less than 0.12 seconds.
- Discordance (located on opposite sides of the isoelectric line on the ECG) of the tooth T relative to the QRS.
- The cogs P associated with the ventricular QRS-complexes.
Treatment of paroxysmal ventricular tachycardia
Unstable ventricular tachycardia usually requires no treatment, however, its forecast for the order deteriorates in the presence of concomitant lesions of the heart. In the classical stable tachycardia necessarily emergency relief of paroxysmal attack.
Before conducting medical procedures to restore normal heart rhythm in this pathology it is important to consider the following factors:
- Had there been any earlier arrhythmia; it hurts the patient with thyroid disease, cardiovascular system.
- Have there been any unexplained loss of consciousness.
- If relatives suffer from these diseases, were among them cases of sudden cardiac death.
- Did the patient any medications (be aware that some medicines (antiaritmiki, diuretics, etc.) may provoke arrhythmias). It is important to remember about the incompatibility of many antiarrhythmic drugs (especially within 6 hours after admission).
- What drugs was restored the rhythm earlier (is one of the indications for this drug).
- Were there complications of arrhythmias.
Stages of relief of an attack of paroxysmal ventricular tachycardia:
Any tachycardia with advanced QRS-complex (including supraventricular with aberrant conduction) and severe disorders of hemodynamic parameters are shown electrical cardioversion (cardioversion). For this purpose, the category of 100 to 360 joules. In the absence of effect simultaneously intravenously injected a solution of Adrenalin with one of the antiarrhythmic drugs (Lidocaine, Amiodarone).
If ventricular tachycardia is not accompanied by disruption of blood flow and a pronounced decrease in blood pressure (BP), we first apply the Lidocaine. If no effect is shown electroimpulse therapy (EIT).
In the case of improving the General condition of the patient and increase in blood pressure, but still disturbed heart rhythm, appropriate use of Procainamide. If the condition is not improved by EIT, intravenous solution Amiodarone. In case of successful relief of an attack of ventricular tachycardia is required the introduction of one of the above anti-arrhythmic drugs during the day.
It is important to remember:
- when complete atrioventricular block introduction of Lidocaine is not acceptable;
- in ventricular tachycardia type “Pirouette” relief of paroxysm should begin with the intravenous administration of a solution of Magnesium sulfate.
If ventricular tachycardia is not accompanied by a dysfunction of the left ventricle (no AP reduction and deficiency of blood circulation), the prognosis is favorable and the risk of recurrent attack and sudden cardiac death is minimal. Otherwise, Vice versa.
Paroxysm of tachycardia type “Pirouette” in any course has a poor prognosis. In this case, a high probability of developing ventricular fibrillation and sudden cardiac death.
Prevention ventricular tachycardia
The main prevention of disease is a constant intake of anti-arrhythmic anti-relapse drugs. Individual effective selection of medicines is possible only in half of the patients. Currently use either Sotalol or Amiodarone. When the transferred myocardial infarction as prophylaxis for ventricular tachycardia are drugs such as:
- statins – reduce levels of blood cholesterol (Atorvastatin, Lovastatin);
- antiplatelet agents – prevent the formation of blood clots (Aspirin, Polcard, Aspirin-KARDIO);
- ACE inhibitors – lower blood pressure and relax vascular wall, thereby reducing the load on the heart muscle (enalapril, lisinopril);
- beta-blockers (Bisoprolol, Metoprolol).
After repeated attacks on a background of reception of the above drugs to prevent subsequent paroxysms use:
- implantation of a cardioverter-defibrillator, which in the case of rhythm disturbances in automatic mode gives a certain level to restore normal cardiac activity;
- RF ablatio – physical removal of the pathological pathways of nerve impulses inside the heart;
- heart transplant (in extreme cases, failing other treatment).
Thus, ventricular tachycardia is the worst variant of paroxysmal tachycardia, often accompanied by serious complications. In this abnormal heart rhythm high probability of death.